Brake



March 18, 1941. A. A. LOWEKE BRAKE Filed Nov. 13, 1939 INVENTOR.

. m/f/rf ATTRNEY.

aiented is, i941 UNITED STATES PATENT OFFICE draulle Brak poraticn of California e Company, Detroit, Micla, a cor- Application November 13, 1930, Serial No'. 304,233

76mins.

i i 11 invention relates ,to brakes. and more particularly to automatic adjusters for the friction elements of brakes.

An object of the invention is to provide means for automatically adjusting the friction elements .of a brake to compensate for wear of the linings on the friction elements. Another object of the invention is to provide an automatic adjuster for. the friction elements of a brake controlled by the wear of the lining on the friction element and operative to adjust the element in proportion to the wear on the Another object of the invention is to provide an automatic adjuster for the friction elements of a brake operative in such a manner as to avoid moi-adjustment of the friction element.

A feature of the invention is a member frictionally clamped to a friction element and movable transversely thereon for cooperation with a drum and a retractile stop. and a retractile spring connected directly to the member.

Other objects and features of the invention will taken in connection with the accompanying drawing forming apart of this specification, and in which- Fig. 1 is a vertical sectional view of a brake embodying the invention; Fig. 2 is a sectional view substantially on line 2-4, H8. 1; and i i Fig. 3 is a fragmentary view illustrating a modiiication of the invention. 7 Referring to the drawing for more specific details of the invention, I I represents a fixed support or backing plate adapted to be secured to an axle or to an axle housing, and associated with the backingplate is a rotatable drum i2 adapted to be secured to a wheel.

A pair of corresponding interchangeable iriction elements or shoes I4 and II are supported on the backing plate for cooperation with the drum. As shown, each of the shoes includes a web I! supporting a rim 2| having secured thereon a lining 22 for frlctionaliy engaging the drum.

Each 0! the shoes has mounted thereon an automatic adjuster indicated generally at 24, and adjustable retractile stops 3! are supported on the hacklns plate for cooperation with the adjusters'to support the shoes when the brake is at rest in proper spaced relation to the drum. A retractiie spring 28 connecting the adjusters It serves to return the shoes uponcompletion of a operation to the position of rest and to yleidingly retain them in such position, and a more fully appear from the following description fluid pressure actuated motor a mounted on the backing plate between the separabieends of the shoes It and it is operative to actuate the shoes into engagement with the drum l2 against the resistance of the retractlle spring a. 5 Each of the shoes has an opening 32 extended through its rim 2! and lining 22, and a block 34. preferably of a lower coemcient of friction than the lining 22 on the shoe, is movable in the opening transversely of the shoe. As shown, the block has an arcuate end It adapted to engage the drum, and the other end of the block is rounded as indicated at 3| for cooperation with the associated retraotile stop it. The block has a longitudinal slot I for the reception of a bolt 42 mounted on the shoe. The wall defining the opening 82 through the rim and lining of the shoe and the bolt 42 serve to guide the block during movement thereof, and a spring 44 sleeved on the bolt between washers 4| and II and held 20 under compression by a pin I passed diametrically through the bolt serves to frictionally clamp the block to the shoe. 7

That end of the block adapted to engage the retractile stop is provided with a transverse aper- 25 ture I! for the attachment of the retractiie spring 28. It is, of course, to be understood that the load on the compression spring 41 is greater than the tensile strength of the retractile spring 28.

A modification of the invention 'is'illustra'ted in Fig. 3. In this embodiment of the invention,

a shoe 00 including a web 82 supporting a rim N having, a lining I. has an opening I. throughits rim and lining, and mounted in the web of the shoe is a bolt is. 35

A block I! movable transversely of the shoe in the opening II has a longitudinal slot I4 for the reception of the bolt ll. The block is guided during movement thereof by the wall defining the opening II and the bolt IO, and a spring I6 4 sleeved on the bolt and, held under compression by a pin 18 passed transversely through the bolt serves to frictionally clamp'the block I! to the shoe. One end of the block is curved as at 8| for engagement with the drum, and the other 4 end ofthe block is rounded as at I! for cooperation withan adjustable'retractile stop 84.

A link it has one of its ends pivoted to the block 12 adjacent the rounded end thereof. The

other end of the link is pivoted to the shoe I, 50

and a retraotile spring II is connected to the link. This structure has a marked advantage in that? the load on the spring I! may be greatly reduced to the end that the force required to move the block 12 against the frictional resistance imposed by the spring I6 need not be materially greater than the tensile strength of the retractile spring.

Under normal operating conditions, upon energization of the motor 30, the shoes H and [6 are actuated into engagement with the drum l2 against the resistance of the retractile spring 28 to effectively retard rotation of the drum. This operation results in wear of the linings 22 on the friction elements or shoes, and because of this condition, when the shoes are returned to the position of rest upon the conclusion of a braking operation, under the influence of the retractile spring 28 against the stops 26, they are not supported in proper spaced relation to the drum. Accordingly, during a subsequent braking operation greater movement of the shoes is necessitated.

In the present invention, when the shoes are actuated into engagement with the drum, the automatic adjusters 24 engage the drum simultaneously with the shoes, and because of a difierential in the coefficient of friction of the linings 22 on the shoes and the blocks 34, as the lining on the shoes wears, the blocks 34 are moved relative to the shoe against the resistance imposed by the compression springs 44. This movement of the blocks is proportionate to the wear on the linings 22, and is governed entirely by the wear on the linings, hence when the shoes are returned to their retractile position on the stops 26 they aresupported in proper spaced relation to the drum.

In automatic adjusters of this particular type, there is a tendency toward under-adjustment of the shoes, due to the snapping action of the retractile spring, generally connecting theshoes,

occurring at the conclusion of a braking opera-' tion. To avoid this undesirable condition, the retractile spring is connected between the adjusters 24, and the compression on the spring 44 has a greater strength than the tensile strength of the retractile spring, and, furthermore, the' path of movement of the block of the adjuster is angularly disposed to the force imposed by the retractile spring.

In the modified form of the invention, the retractile spring I6 is connected to the link 86 having one end pivoted to the shoe 60 and its other end pivoted to the block 12. By this arrangement, the compression strength of the spring 16 may be greatly reduced to the end that but little force may be required to move the block when engaged with the drum.

While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A brake comprising a rotatable drum, a friction element for cooperation therewith, a retractile stop associated with the element, a member frictionally clamped to and movable transversely of the element for cooperation with the drum and stop, and a retractile spring connected to the member.

2. A brake comprising a rotatable drum, a friction element for cooperation therewith, a retractile stop for the friction element, a member frictionally clamped to .the element and movable transversely thereof for cooperation with the drum and stop, and a retractile spring connected to the member imposing force at an angle to the path of movement of the member.

3. A brake comprising a rotatable drum, a friction element for cooperation therewith, a retractile stop for the element, a member frictionally clamped to and movable transversely of the element for cooperation with the drum and stop, means for guiding the member during movement thereof, and a retractile spring connected to the member imposing force at an angle to the path of movement of the member.

4. A brake comprising a rotatable drum, a friction element for cooperation therewith, an adjustable retractile stop for the element, a member frictionally clamped to'and movable transversely of the element having a part for cooperation with the drum and a rounded end for cooperation with the stop, and a retractile spring connected to the member imposing force angularly disposed to the path of movement of the member.

5. A brake comprising a fixed support, a rotatable drum associated therewith, a pair of friction elements mounted on the support for cooperation with the drum, adustable retractile stops for the friction elements, adjusters for the friction elements including members frictionally clamped to and movable transversely of the friction elements for cooperation with the drum and stops, and a retractile.spring connecting the a I members.

6. A brake comprising a rotatable drum, a friction element for cooperation therewith, a retractile stop associated with the element, a member frictionally clamped to and movable transversely of the element, linkage connecting the member to the friction element, and a retractile spring connected to the linkage.

'7. A brake comprising a rotatable drum, a friction element for cooperation therewith, a retractile stop associated with the element, a member frictionally clamped to and movable transversely of the element for cooperation with the drum and stop, a link having one of its ends pivoted to the member and its other end pivoted to the element, and a retractile spring connected to the link.

AARON A. LOWEKE. 

